Reversing rudder



Sept. 8; 1925. 1,553,090 A. MCNAB REVERS ING RUDDER Filed Nov. 22. 1924 Mmmm M9 Nav NTOI? l -lNvE vArm/mfr Mam Cil

Patented Sept. 8, 1925. i

ALEX-.A1\TIDERiillflclq'Al.y ,BBIDGEPO-BT, CONNECTICUT; f

REvns'INe RUDDER..

y Application'ledN-ov'ebi' 22,' 1924;' 1 Serial No. 751,446.

To all whom t may comem- K Be it known that I,- 'ALEXANDER.MONAB, a subject'ofthe King of Great Britain, rei siding at Bridgeport, Connecticut, have invented certain new and useful Improve# ments'in ReversingfRudders, of-which the following-is a specification.

The present invention particularly` Jrelates to improvements in the rudder set forth in the prior United States Patents Nos. 1,186,- 2l0=and 1,467,521 to which reference is made for any fuller'informationdesired as to the characteristic features thereof.; The descrip'- tion" of the known features ofthe rudder' in the kpresent application is limited to only Suchdetails a's'are necessary' to a clear 'comprehension' ofV the' improvements contemplatedbfy` the presentninvention. A

It'. has been found' in- `actual, operation of craft fitted with the rudder that the pro* vision of a really tight closure of the two rudder plates whengoing astern was vditicult', to'altta'in owing to mechanicalconsiderations. Even'when theabutting edges of the rudder pla-tes hadreceive'dja carefulfnishing yoperation to make a satisfactorily tightjoint"`un'dernormal conditions, the application Aof power accide-ntallyor through some s lightlack 'of"pr,ecisioninithej operating gear, for evenl a fewfinst'ants afterthe plates had come into contact', wasliablelto cause the meetingedges: to be4 sprunggap'art, thusj perm'ittingwater` to. escape therebetween and lessen'ing the effectiveness of'the rudder.' 4

A. further point to befconsideredin formin'g the rudder' was to guard against' buckling of the rudder plates 'when stoppingthe wavy ofthe ship. This necessitated'the' provision of relatively `heavy gauge plates in the form of construction set forth inthe prior applications.l

The aiml of this invention is' tobpro'vide a construction by whichthe above described drawbacks of the known'construction-of the rudders are -obviated,.` a'ni'u'ch7 improved p Y n p by asolidasfhaft6'and theother'by alholclosure ofthe rudder' platesbeing obtained while the weight 'ofthe' rudderjplates'islnot Yincreased' and in .fctfmay be'y considerably reduced. s

The obj ect Qof' the -invention is' to provide a rudderofthe kind described with 'corrugations adjacent-the meetingedges' oft the rudder plates, saidcorrugations being formed lO 'perniit the'A meeting edges to' slide v'slightly v one over the other should said plates be forced toward one another'after their meeting edges' come into contact.

A further objectof theinvention'is to proe vide arudder of the kind describedlwitha plurality'y of p strengthening corrugations spaced fromoneH adjacent the leading edge to4 one adjacentl theo` trailing edge'VV of the plates.

A further object of the invention is to provide arudder ofthe kinddescribedhaving segmentali corrugations *extendingver'- tically throughout the'length ofthe rudder plates. Y

i A1 further object of the'inven'tion" is to provide'afru'dder ofthe kind described with corrugations forthe the purpose described ofsuch size as tocause' no'materialincrease inthe skin friction ofthe rudder.

.Further objectso'fv theY invention Vwill here'- in'after' appear and be'specifically pointed outuinlthe appended claims;

The invention'is illustrated inthe accompanying drawings in which#- Fig; lisa perspective view oftheruddr formed accordingto the present invention.

Fig.' Qis a .planrview' of the' rudder' constructed 'according'to my invention, the' rudder'plates being shown'in closed'positio'n' inY order to' reverse the ship or boat;

. Fig.` 3 is a'detail cross ,sectional view s'how' ing the relatively`small.size'of.tl1e corrugations.

The Kitchen rudderA withtheY improvement of which "the presenti invention'r is concerned, consists. essentially oftw'o bladesl, 1 eachsubstantially' semicircular. in vertical section and pivoted together vertically preferably so as' to surround the propeller. TheV blades are so shapedialong the rear vertical'edge thatithey may be lb'roughtinto conltact Ythroughjout.y the length of said 'rear edge,

their inner 'faces then being substantiallyat right angles and preventing the passage/of any water therebetween.

.ofthe b'lade's'ordefle'ctors isv operated low" shaft 7 concentricv :with theisolid shaft.

lBy suitable mechanism the"'deflectorszor .rud-

ders are made' toturn'togetherin the same. direction orre'quallyl inf opposite directions.

To be as effective as possible' the'vv rudder should" bjej placed.:y in', .or rvnear', .the propeller race. This ensures"that.the speedY of the Vwater'"pt rssing 'everthe rudderwll be greater than the speed of the vessel through the water by a varying value which may be as much as 30 per cent; and that in starting the ship from rest there will be a flow orf water over the rudder, giving steering power before the vessel has much weight on. This is effected in the most efficient way possible, since not only lare the blades in the propeller race but confine the race adjacent the propeller.

Varia/imio]T Speerl-ll`or ordinary direct speed ahead the rudder will be opened until nearly parallel, being slightly less at the after end. When the defiectors are partially closed, the speed of the boat will be reduced to about one-halfl the full ahead speed, the engines still running at the same revolutions. `When the rudders are closed still further the boat will remain stationary. In this case the forward thrust on the propeller is balanced by an equal astern thrust on the rudders. 'When the deflectors are closed together, the reaction on the rudders causes the vessel to go astern. 'I`his position gives the maximum astern speed.

Steering/. The vessel can be steered by carrying helm on the rudders, whether they be fully open, partially closed or quite closed. It has been found that degrees to degrees of helm is quite sufficient f-or all practical purposes, although with ordinary rudders as much as 88 degrees or even l0 degrees of helm is used. This limitation of helm angle tends to decrease of size in the steering gear. Under these conditions the vessel can be made to turn about on axis somewhere near .her middle length without moving ahead or astern.

It will be understood from the description of the arrangement and working of the rudder that it is subjected to very considerable stresses and in order to resist these coinpletely as is necessary to avoid deformation tending to prevent the rudders from closing properly, it has been hitherto necessary to make the rudder plates from relatively heavy metal, this in turn imposing a greater load on the operating gear. Even when the rudder blades are of material suiiiciently heavy to prevent buckling or distortion under normal working, it is very easy, particularly when using power rudder control, to damage the rudder by continuing the closing movement lof the rudder plates after they have come into contact. This results at least in causing the plates to buckle along their meeting edges, allowing water to escape therebetween.

To both provide a. construction of plate which will not be readily damaged in the way described and to reduce their weight, I provide the plates with corrugations er:- tending preferably the full length 4of the plate, a corrugation extending adjacent or along the meeting edges of the plates. The

free edge of the plate, i. e. between said corrugation along the meeting edges of the plates and the edge of the plates, or the edge of the corrugation itself, is formed as a groove, a segment of a circle concentric with that from which the co-operating corrugation or bend on the col-operating plate is struck. The result of this construction is that not only do the edges of the plates nest securely together without the careful finishing of the meeting edges hitherto necessary, but any accidental application of power after the said meeting edges have come into cont-act does not cause the plates to spring away from each other along portions of said edges which are enabled to slide for a limited but sufficient amount over one another while maintaining an efficient closure preventing the passage of water between the plates.

In the drawings Fig. l shows the rudder mounting and the arrangement of the grooves in the rudder plates l, 1. Fig. 2 indicates the trailing edge groove in one plate while 3 indicates the corresponding groove in the other rudder plate. In the rudder illustrated the mating joint is formed between the edge of the plate lying beyond the groove 2 and the side of the corruga-v tion 3. As previously described the edge of the plate 2 is bent into a segmental groove concentric with the groove 3 with the result that the edges nest securely together and can worlr or slide over one another to the slight extent liable to occur in practice without distorting the plates or causing the edges to spring apart. Y

The grooves 2, 3 act to reinforce the trailing edge of the rudder while the grooves 5 act similarly to strengthen the forwardedge of the rudder. Any desired number of cor rugations may be formed in the plates intermediate the forward and rear corrugations, in the rudder illustrated a single groove 4 being shown.

The provision of these corrugations has been found to effect important increases in the strength for weight of the rudder, enabling a lighter gauge of sheet metal to be employed while obtaininga more rigid construction.

The functioning of the rudder is also much improved both by the resistance to injury by faulty handling and to the better closure obtained. i

It is to be understood that I do not desire to limit myself as to the number or characteristics of the grooves or corrugations provided in the rudder plates. Any form of corrugation, annular, or of various curvatures may be employed provided the desired result is obtained, the most .suitable form being determined by consideration of the various factors involved such as gan-'ge of metal or .ease of manufacture. The form described and illustrated in the drawings has been found to give very satisfactory results in actual practice.

I declare that what I claim isl. In a rudder for ships or boats comprising two plates pivoted to be movable from a position of substantial parallelism to a position in which the trailing edges contact with one another, the provision of corrugations adjacent the meeting edges of the rudder plates, said corrugations being formed to permit the meeting edges to slide slightly one over the other should said plates be forced toward one another after their meeting edges have come into contact.

2. In a rudder for ships or boats comprising two plates pivoted to be movable from a position of substantial parallelism to a position in which the trailing edges contact with one another, the provision of strengthening corrugations spaced from one adjacent the leading edge to one adjacent the trailing edge, the latter corrugations on the two plates being arranged to form a mating joint.

3. A rudder for ships or boats comprising two platesI bent into semicircular form and pivoted together on a vertical axis so as to be movable between a position of substantial parallelism anda position in which the rear or trailing edges of the plates make a tight joint, provided with vertically arranged corrugations segmental in form.

4. A rudder for ships or boats comprising two plates bent into semicircular form and pivoted together on a vertical axis so as to be movable between a position of substantial parallelism and a position in which the rear or trailing edges of the plates make a tight joint, provided with corrugations arranged to extend from or adjacent one of said pivots to or adjacent the other pivot.

5. In a rudder for ships or boats comprising two plates pivoted to be movable from a position of substantial parallelism into a position in which they contact with one another along one edge, the provision of corrugations of such a depth as to cause no appreciable increase in the skin friction of the rudder, the corrugations at or near the rear edge of the plates forming a mating joint capable of a certain amount of sliding movement over one another while maintaining a tight closure preventing the passage of water between the plates.

In testimony whereof I have aixed my signature.

' ALEXANDER MCNA B. 

